Peristaltic roller pumps are generally used whenever the pump environment requires that the pump mechanism not contact the fluid to be pumped. Such pumps are widely used in the medical profession for pumping blood and other fluids wherein it is desired to maintain the blood or fluid in a sterile environment without the possibility of contamination from the pump mechanism.
While the art of designing and building roller pumps has been relatively well developed over the years, problems associated with pump surge, undue complexity, and entanglement or kinking of the flexible tubing still persist.
U.S. Pat. Nos. 2,804,023 to J. C. Lee entitled "Pump" and 3,787,148 to Kopf entitled "Roller Pump" both disclose concepts for minimizing surge and providing a relatively constant driving torque or pump output. Kopf, in particular, discloses a pair of rollers on reciprocating pump arms 14 and 15, which are spaced 180.degree. from one another, and which engage a semicylindrical wall. Lead in and lead out ramps 60, 61 are provided.
Applicant has found, contrary to Kopf's teaching, that surge may be minimized by rendering the semicylindrical wall a full 180.degree., and providing first and second surge radii beyond the 180.degree. arc, as will be hereinafter more fully described.
U.S. Pat. Nos. 3,885,894 to Sikes entitled "Roller-Type Blood Pump" and 4,095,923 to Cullis entitled "Peristaltic Pump with Accommodating Rollers" are representative of a large number of patents which disclose fingers or arms in front of the pump rollers to assist in positioning the flexible tubing against the semicylindrical wall for roller engagement. The Sikes reference, in particular, discloses rectilinear sweep arms that extend outwardly from the rotor in front of the rollers and their reciprocating pump arms. It has been found, however, that even with the arms of the type generally disclosed by Sikes and Cullis, small diameter tubing may still become jammed or kinked by the mechanism. Applicants have found that by replacing these rectilinear arms with sloped or angled sweep vanes, the problems of jamming or kinking are eliminated.
U.S. Pat. No. 4,174,193 to Sakakibara entitled "Peristaltic Pump with Hose Positioning Means in Pressure Adjustment Apparatus" discloses a pump having means to rapidly adjust the position of the rollers with respect to the pump wall. Applicants have developed a structure that may be inexpensively fabricated from a minimum number of moving parts that will enable precise placement of the rollers with respect to the pump wall with a single adjustment. The mechanism utilized, as will be hereinafter more fully described, is substantially simpler than the mechanisms disclosed in the foregoing patent.